Invasion, dispersion, population persistence and ecological impacts of a freshwater mussel (Limnoperna fortunei) in the Honshu Island of Japan

The freshwater mussels Limnoperna and Dreissena require the low advective flow conditions of large continental rivers so their larvae can develop sufficiently to settle before reaching the ocean in order to maintain their populations. However, these species have also invaded some island rivers with high advective flows. We integrated data for the invasion, distribution, genetic composition and ecological impacts of L. fortunei on the Honshu Island of Japan. Invasion route and mechanisms of dispersion and population persistence are detailed in non-continental rivers. The initial invasion and several of the dispersions of L. fortunei were closely related to the food culture of consuming freshwater clams in Japan. Other dispersions were most likely affected by head-race channels. Thus, population persistence depends on anthropogenic lentic environments such as reservoirs and channel networks as a nursing habitat for L. fortunei larvae. L. fortunei was often abundant near artificial habitats and less abundant in the lower segments of rivers. We also contrast the invasion processes of freshwater mussels in continental and non-continental rivers.